Amoussou was born in Draguignan, France. His martial arts background is in judo, his older brother Bertrand being a medal-winning judoka for France in the 1990 European Judo Championships, while Amoussou's Senegalese father was also a successful karate stylist. Before becoming a full-time fighter, Amoussou worked full-time as an undercover agent in his native France, mostly tracking down drug dealers and thieves.
Amoussou (nicknamed Psycho) is a member of the Team France and Team "Haute Tension". His trainers are one time PRIDE Fighting Championship fighter and older brother Bertrand Amoussou.
Amoussou was set to headline M-1 Global Presents: Breakthrough against top contender Nick Thompson but his opponent was later changed to journeyman John Doyle due to an injury Thompson suffered during training.
Amoussou signed an exclusive four fight contract with top Japanese promotion Dream and North American promotion Strikeforce. He fought in Strikeforce against UFC veteran Trevor Prangley and in Dream against Pride veteran Kazuhiro Nakamura. In April 2011, he defeated Nathan Shouteren via decision after a spectacular fight where he showed his "Psycho" style again.
In November 2010, he went to The Ultimate Fighter selections in Las Vegas, but his weight class was not selected.
Amoussou then signed for Bellator and he made his debut on May 21, 2011 against Sam Alvey at Bellator 45, losing via split decision. He rebounded with a TKO victory over Jesus Martinez at Bellator 59 in November 2011.
Amoussou then took part in the Welterweight Tournament scheduled to take place in Bellator's sixth season. He was expected to fight War Machine in the opening round of the tournament at Bellator 63. However, War Machine was sentenced to a year in prison for an assault in Las Vegas, Nevada and was forced out of the bout and the tournament. Instead, he faced Chris Lozano and won via submission in the first round.
In the semifinals at Bellator 69, Amoussou faced undefeated David Rickels. The bout was back-and-forth with Amoussou on the receiving end of multiple groin shots. In the end, Amoussou won the fight via split decision.
Amoussou faced Bryan Baker on July 20, 2012 in the finals at Bellator 72. He won the fight via submission in just under a minute, earning $100,000 and a title shot. He faced welterweight champion Ben Askren in Bellator's seventh season in the fall of 2012. He then lost by TKO to Askren for the title.
Amoussou next faced promotional newcomer Paul Bradley on October 18, 2013 at Bellator 104. He lost the fight via unanimous decision. Amossou then faced David Gomez on April 18, 2014, at Bellator 117. He won fight via split decision, snapping his two fight losing streak.
Amoussou faced Fernando Gonzalez at Bellator 122 on July 25, 2014. He lost the fight via unanimous decision.Bellator Fighting Championships
Bellator Season 6 Welterweight Tournament Championship
2012 Bellator Submission of the Year (against Bryan Baker)